Extra high output and high output fluorescent lamps

ABSTRACT

An extra high output or high output fluorescent lamp comprises first and second fluorescent layers superposed on each other. The first fluorescent layer contains at least 10 percent by weight of manganese activated magnesium fluorogermanate on the basis of the entire first layer. The second fluorescent layer consists of calcium halophosphate activated by antimony and manganese. The aforementioned fluorescent lamp displays a reduced attenuation of luminous fluxes relative to operating duration.

United States Patent [72] Inventors Teizo Hanada Saitama-ken;

Akira Someya, Yokomaha-shi, Japan [2]] Appl. No. 786,958

[22) Filed Dec. 26, 1968 [45] Patented Mar. 23, 1971 [73] Assignee TokyoShibaura EIectric Co., Ltd

Kawasaki-shi, Japan [32] Priority Dec. 29, 1967 [54] EXTRA HIGH OUTPUTAND HIGH OUTPUT FLUORESCENT LAMPS 6 Claims, 2 Drawing Figs.

[52] US. Cl 313/109 [51] Int. Cl H01j61/44 [50] FieIdofSearch 313/109 [56] References Cited UNITED STATES PATENTS 2,135,732 11/1938 Randall etal 313/109 2,424,454 7/1947 Gordon 313/109 2,452,518 10/1948 Burns 3 I3/109X 2,965,778 12/1960 Jenkins etal. 313/109X 3,114,067 12/1963I-Ienderson...... 313/109 3,287,586 11/1966 Bickford 313/109 3,409,792 1H1968 Martyny et a1 313/109 OTHER REFERENCES I. FLUORESCENT LAMPS ANDLIGI-I'ITNG, BY ELEN- BAAS ET AL, CHAPTER III, Sections 3.9- 3.12appearing on pages 58- 64; 1962; copy of book in AU. 251. II. LIGHT ANDPLANT GROWTH, BY VANDER VEEN ET AL, PHILIPS TECHNICAL LIBRARY, 1959,PAGES 123 & 125, copy ofpages 1 17- 125 in 3 l3 109 LIT.

Primary Examiner-John Kominski Assistant Examiner-Pa1mer C. DemeoAttorney-Flynn & Frishauf ABSTRACT: An extra high output or high outputfluorescentlamp comprises first and second fluorescent layers superposedon each other. The first fluorescent layer contains at least 10 percentby weight of manganese activated magnesium fluorogermanate on the basisof the entire first layer. The second fluorescent layer consists ofcalcium halophosphate activated by antimony and manganese. Theaforementioned fluorescent lamp displays a reduced attenuation ofluminous fluxes relative to operating duration.

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INVENTORS EXTRA HIGH OUTPUT AND HIGH OUTPUT FLUORESCENT LAMPS Thepresent invention relates to a fluorescent lamp and more particularly toextra high output and high output type fluorescent lamps of good colorrendition which have been prominently improved in performance.

For improvement of the color rendition of a fluorescent lamp, it hasbeen general practice to mix several kinds of fluorescent substancessuch as magnesium tungstate, calcium tungstate, manganese activated zincsilicate, tin activated calcium-strontium orthophosphate, tin activatedstrontium-magnesium-barium orthophosphate and manganese activatedmagnesium arsenate, and to coat said mixture on the inner wall surfaceof the glass tube to form a fluorescent layer thereby to make uniformthe spectral energy distribution of said lamp over the entire visibleregion.

However, the aforesaid fluorescent layer had the drawback that when itis applied in an extra high output or high outputtype fluorescent lampwhich receives large inputs per unit length of the glass tube it causesthe luminous flux of the lamp to be noticeably decreased while it waslighted. Further, when the layer is used in the aforementioned types offluorescent lamps, outputs of the continuous spectral portion sharplydrop as compared with those of the visible spectral lines of mercury asexhibited by the lamp in operation, with the resultant wide variationsin the color temperature thereof. (This failure is aggravated, becauseoutputs having a wavelength of 436 nm. involved in the spectral lines ofmercury are extremely large.) There are further shortcomings, forexample, that the tube wall of such fluorescent lamps rises intemperature to as high as 80 to 200 C., resulting in the reducedbrightness of the fluorescent layer.

To eliminate the above-mentioned drawbacks, it may be contemplated touse a fluorescent material stable to heat and ultraviolet rays, suppressoutputs of the spectral lines of mercury, particularly those having awavelength of 436 nm. or improve the quality of gases to be sealed inthe glass tube so as to improve the performance of the lamp.

The object of the present invention is to provide an extra high outputand high output type fluorescent lamps of good color rendition which areprominently improved in performance.

According to the present invention, an extra high output and high outputtype fluorescent lamps comprise first and second layers of fluorescentlamps comprise first and second layers of fluorescent material. Thefirst layer contains at least percent by weight of manganese activatedmagnesium fluorogermanate, a fluorescent material most stable to heat.The second layer deposited on the first layer consists of calciumhalophosphate activated by antimony and manganese. Such type offluorescent lamp is improved prominently in performance and appreciablyin color rendition.

According to the present invention, there is provided a fluorescent lampcomprising a light transmissible sealed envelope, coil electrodes sealedto both ends of said envelope, a quantity of mercury and an ionizableinert gas sealed in said envelope, and a fluorescent layer memberdeposited on the inner wall surface of said envelope and having anominal rated lamp current of 0.8 to 1.5 amperes, said fluorescent layermember comprising a first fluorescent layer consisting of manganeseactivated magnesium fluorogermanate, deposited on the inner wall surfaceof said tube and having a thickness of 5 to 30 microns and a secondfluorescent layer consisting of calcium halophosphate activated byantimony and manganese, deposited on said first fluorescent layer andhaving a thickness of 5 to microns.

The present invention can be more fully understood from the followingdetailed description when taken in connection with the accompanyingdrawing, in which:

FIG. 1 illustrates an extra high output fluorescent lamp according to anembodiment of the present invention with part broken away and shown insection; and

FIG. 2 is a curve diagram showing the spectral distribution of theoutput of the extra high output-type fluorescent lamp shown in FIG. 1.

There will now be described by reference to the accompanying drawing thepreferred examples of the present invention which follow. It will beunderstood, however, that they are offered only by way of illustrationand are not intended to restrict the scope and breadth of the inventionor to limit the scope of the patent claims attached hereto.

EXAMPLE 1 There was deposited by the known method a paint consisting ofmanganese-activated magnesium fluorogerrnanate on the inner wall surfaceof a light transmissible sealed envelope 1 having an external diameterof 38 mm. and a length of about 1200 mm. and provided with neckconstricted portions 2 at both ends, thereby to form a first layer 3 offluorescent material 20 microns thick. On said layer 3 was applied bythe known method a paint consisting of calcium halophosphate activatedby antimony and manganese to form a second layer 4 of fluorescentmaterial 10 microns thick. To both ends 63 of the envelope 1, on theinner wall surface of which were deposited the aforesaid fluorescentlayers 3 and 4, were sealed coil electrodes including platelikeauxiliary electrodes 5 and adhered recessed double contact bases 6 eachhaving a pair of contacts. After the envelope was evacuated, a quantityof mercury and a gas mixture consistng of 5 percent He, 38 percent Ne,and 57 percent Ar, all percentages being by volume, was sealed in saidenvelope soas to beused as the ionizable inert gas. Thus was prepared anextra high output-type fluorescent lamp operable at the nominal ratedwattage of l 10 w. and nominal rated lamp current of 1.5 amperes.

Comparison of the properties of said extra high output lamp and those ofthe conventional similar lamp is given in the table below.

I Ra denotes the general colour rendering index by a test colour methodas specified by the Commission Internationale de lEclairage (C.I.E.).

2 Preservation of Luminous Flux at 1,000 Hour Operation.

3 Preservation of Luminous Flux at 3,000 Hour Operation.

As clearly seen from the above table I, an extra high output fluorescentlamp according to the present invention presented good color renditionand prominently improved performance. In other words, The presentfluorescent lamp suffered less reduction in the luminous flux while itwas used, proving usable for a longperiod under good conditions.

FIG. 2 shows the distribution of spectral energies of the aforementionedw. extra high output-type fluorescent lamp. The abscissa representswavelengths in nm. and the ordinate relative energies in percentage. Therectangular blocks in the FIG. represent output light beams havingwavelengths of 405, 436, 546, and 758 nm. corresponding to the spectrallines of mercury. As apparent from the FIG., the present fluorescentlamp provides a good projection of light beams particularly having awavelength of 655 nm. (a deep red color) and excellent color rendition.Further, since the spectral line of mercury having a wavelength of 436nm. is controlled to a low level, the lamp exhibits less variations inthe color temperature.

EXAMPLE 2 On the inner surface wall of a glass envelope having the samedimensions as that of example 1, was deposited a mixture of fluorescentmaterials consisting of 70 percent by weight of manganese-activatedmagnesium fluorogermanate and 30 percent of manganese-activatedmagnesium boroarsenate to form a first fluorescent layer 20 micronsthick. On said layer was deposited calcium halophosphate activated byantimony and manganese to form a second fluorescent layer l micronsthick.

Later in the same manner as in example 1, there was prepared an extrahigh output-type fluorescent lamp operable at the nominal rated wattageof 110 w. and nominal rated lamp current of 1.5 amperes. Comparison ofthe properties of said extra high output-type lamp with those of theconventional similar lamp gave almost the same results as in table 1.The distribution of output spectral energies was substantially the sameas that shown in FIG. 2.

EXAMPLE 3 On the inner surface wall of a glass envelope having the samedimensions as that of example 1, was deposited a mixture of fluorescentmaterials consisting of 50 percent by weight of manganese-activatedmagnesium fluorogennanate, 30 percent by weight of manganese-activatedmagnesium boroarsenate and 20 percent by weight of manganese activatedmagnesium arsenate to form a first fluorescent layer 20 microns thick.On said layer was deposited calcium halophosphate activated by antimonyand manganese to form a second fluorescent layer microns thick.

Later in the same manner as in example I, there was prepared an extrahigh output fluorescent lamp operable at the nominal rated wattage of 110 w. and nominal rated lamp current of 1.5 amperes. The properties ofsaid extra high output lamp and the distribution of output spectralenergies therein were almost the same as in example 1.

EXAMPLE 4 On the inner wall surface of a glass envelope 38 mm. inexternal diameter and about 2,400 mm. long (As is known, a highoutput-type fluorescent lamp does not have neck constricted portions.)was deposited a fluorescent material consisting of manganese-activatedmagnesium fluoreogermanate to form a first fluorescent layer micronsthick.

On said layer was deposited calcium halophosphate activated by antimonyand manganese to form a second fluorescent layer 10 microns thick. Toboth ends of the glass envelope, the inner wall surface of which wascoated with these fluorescent layers, were sealed electrodes and adheredrecessed double contact bases having a pair of contacts. After the glasstube was evacuated, there was sealed an ionizable inert gas onlyconsisting of argon. Thus was prepared a high output-type fluorescentlamp operable at the nominal rated wattage of l 10 w. and nominal ratedlamp current of 0.8 ampere.

Comparison of the properties of said high output-type lamp and theconventional similar lamp is given in the table below.

TABLE 2 Initial luminous Flux, lm. Ra Percentage 2 Percentage 3Conventional Lampv 6,000 79 80 70 Lamp of Example 4" 6, 000 81 89 82 1See Table 1. 2 Preservation of Luminous Flux at 1,000 Hour Operation. 3Preservation of Luminous Flux at 3,000 Hour Operation.

EXAMPLE 5 On the inner wall surface of a glass envelope having the samedimensions as that of example 4, was deposited a mixture of fluorescentmaterials consisting of percent by weight of manganese-activatedmagnesium fluorogermanate and 20 percent by weight ofmanganese-activated magnesium boroarsenate to form a first fluorescentlayer 20 microns thick.

On said layer was deposited calcium halophosphate activated by antimonyand manganese to form a second fluorescent layer 10 microns thick.

Later in the same manner as in example 4, there was prepared a highoutput-type fluorescent lamp operable at the nominal rated wattage of 110 w. and nominal rated lamp current of 0.8 ampere. This highoutput-type lamp exhibited almost the same properties and distributionof spectral energies as in example 4.

In the aforementioned five examples, the first fluorescent layer had athickness of 20 microns and the second fluorescent layer 10 microns.However, experiments show that the thickness of the first layer is onlyrequired to fall within the range of 5 to 30 microns, the optimum valuebeing 20 microns, and that the thickness of the second layer is onlyrequired to range between 5 and 20 microns, the optimum value being 10microns. Thickness outside of the aforesaid ranges fail to achieve thedesired effect.

In the aforesaid examples, the first fluorescent layer consisted ofmanganese-activated magnesium fluorogermanate alone, a mixture ofmanganese-activated magnesium fluorogermanate and manganese-activatedmagnesium boroarsenate or a mixture of manganese-activated magnesiumfluorogermanate, manganese-activated magnesium boroarsenate andmanganese-activated magnesium arsenate. The first fluorescent layer isnot required to have the specified weight percentages. The only criticalcondition is that the weight percentage of the manganese-activatedmagnesium fluorogermanate be at least 10 percent on the basis of thecomposition of said layer. If the content of the aforementioned materialis smaller than 10 percent on the basis of the composition of the firstlayer, the fluorescent layer member as a whole will be prominentlyreduced in luminescing efficiency, when the temperature of the lampenvelope wall approaches C., and considerably degraded under theirradiation of ultraviolet rays. Insofar as the aforesaid criticalcondition is fully met, each of the above-listed mixtures constitutingthe first layer will have the same effect with respect to the propertiesof a fluorescent lamp as when said layer consists only ofmanganese-activated magnesium fluorogermanate.

In the foregoing examples, the weight percentages of antimony andmanganese contained in the calcium halophosphate activated by antimonyand manganese constituting the second fluorescent layer accounted for0.8 percent and 1.0 percent respectively. A fluorescent lamp thusprepared has a color temperature of 3,l00 K. when it is lighted and isbest adapted for general lighting purposes as well as for joint use witha halogen lamp in illuminating a color television studio. However, theaforementioned weight percentages of antimony and manganese do not formthe feature of the present invention, but as is known to those skilledin the art, said percentages may be changed to vary the colortemperature of the lamp We claim:

1. In a fluorescent lamp having a nominal rated lamp current of 0.8 to1.5 amperes, comprising a light transmissible sealed envelope, coilelectrodes sealed to both ends of said envelope, a quantity of mercuryand an ionizable inert gas sealed in said envelope, and a fluorescentlayer member deposited on the inner wall surface of said envelope, theimprovement wherein said fluorescent layer member comprises a firstfluorescent layer comprised of manganese-activated magnesiumfluorogermanate deposited on the inner wall surface of 3. A fluorescentlamp according to claim 1 wherein said first fluorescent layer is 20microns thick.

4.-A fluorescent lamp according to claim I wherein said secondfluorescent layer is l0 microns thick.

5. A fluorescent-lamp according to claim 1, wherein said inert gascomprises a mixture of helium, neon and argon.

6. A fluorescent lamp according to claim I wherein said inert gascomprises a mixture of 5 percent helium. 38 percent neon, and 57 percentargon, said percentages being by volume.

2. A fluorescent lamp according to claim 1 wherein said firstfluorescent layer further contains at least one fluorescent materialselected from the group consisting of manganese-activated magnesiumboroarsenate and manganese-activated arsenate, the weight percentage ofthe manganese-activated magnesium fluorogermanate accounting for atleast 10 percent.
 3. A fluorescent lamp according to claim 1 whereinsaid first fluorescent layer is 20 microns thick.
 4. A fluorescent lampaccording to claim 1 wherein said second fluorescent layer is 10 micronsthick.
 5. A fluorescent lamp according to claim 1, wherein said inertgas comprises a mixture of helium, neon and argon.
 6. A fluorescent lampaccording to claim 1 wherein said inert gas comprises a mixture of 5percent helium, 38 percent neon, and 57 percent argon, said percentagesbeing by volume.